In 2003, the Ministry of Health, Labour and Welfare in Japan presented the official assay using ABI PRISM 7000^® for the detection of Norovirus (NV) genogroups I (GI) and II (GII). We have recently modified the official assay and, using LightCycler^® PCR equipment, have developed the “LC cDNA” and “LC One-Step” detection assays. These two assays enabled detection and quantitation of the NV genome within 6 hrs using the LC cDNA assay, and within 3 hr using the LC One-Step assay. The primers and probes used in both assays were identical to those used in the official assay, because there are no idiosyncrasies between them. The detection limits of our assays for the GI and GII genomes were 10 copies/5 μ l . Results of field samples using both the LC cDNA and One-Step assays were the same. In correlation analysis between log transformed genome copy numbers of the LC cDNA and One-Step assays, fecal samples from food poisoning cases ( n = 27) were y = 0.9627 x -0.1034 ( R ² = 0.9888), and patient samples from a hospital ( n = 22) were y = 1.0064 x -0.3473 ( R ² = 0.9610). Utilizing LightCycler^® PCR equipment, our assays detected NV GI and GII. In particular, the One-Step assay could detect within 3 hrs; hence, it is a very useful laboratory technique for the detection of NV from field samples.